By using the independent ingestive system of infant rats as a model motivational system, we have been able to demonstrate impressive learning abilities in pups as young as 1 day of age. Most recently, we have found that infants show conditioning of components of their ingestive behavior to an odor cue that has been repeatedly paired with oral infusions of milk, and this finding forms the basis of the proposed research. Specifically, I will (1) conduct a detailed developmental analysis of the relationship between pups' responses to milk and their responses to stimuli associated with milk. Then, using these findings as a baseline, I will (2) examine whether infants conditioned at an early age remember specific responses, or whether the responses elicited by the stimulus undergo changes as pups mature. Together, these studies may reveal what infants learn: a specific association between a stimulus and response, or a more general association between a stimulus and feeding. I will also determine the importance of two factors in influencing the stimuli that infants attend to and learn about: (3) internal state, which, may determine the value of milk as a reinforcing stimulus to pups, and (4) prior experiences with a stimulus, which may affect how readily pups later learn about that stimulus. The proposed research should contribute to our understanding of some of the processes involved in learning and memory during early infancy.